You've already been able to badly implement monads in Go for 10+ years. Why wouldn't you be able to implement them in a way that the compiler can enforce correctness of?
If you don't want it don't use it. It's that simple.
No it’s definitely not that simple. Code are read more often than written, no one works in a vacuum, especially not in open source. Also, when in Rome...
If a project's owner feels that strongly about not using generics, that's a choice. No dependencies using generics, no generics allowed in PRs etc. Perfectly doable.